1. Field of the Invention
This invention relates to an auto-lock slide fastener slider composed of a slider body, a pull tab, and a combination of a resilient locking member with a resilient tongue and a cover, which may be substituted by a combination of a mere rigid locking member and a leaf spring disposed between the cover and the rigid locking member, at least the slider body and the cover being made of thermoplastic resin. The invention relates also to an apparatus for molding the cover by injection.
2. Description of the Related Art
In conventional auto-look slide fastener sliders of the described type, for attaching a cover to a slider body, it is known to clench the cover against front and rear cover-attachment lugs of the slider body if both the slider body and the cover are made of metal and also to weld the cover and the slider body together by high-frequency or ultrasonic welding if both the slider body and the cover are made of thermoplastic resin.
In an alternative conventional form, as shown in FIG. 20 of the accompanying drawings, a slider body 1' has front and rear cover-attachment projections 12' extending from the upper wing 7' and terminating respectively in outwardly directed hooks 13', the front cover-attachment projection 12' of which is integral with a pair of pivot supporting portions 15' for supporting a pivot 23' horizontally provided to a locking member, an engaging recess 14' between the pivot supporting portions, and a locking-pawl-insertion hole 16' near a base of the rear cover-attachment projection 12'. And a locking member 3' has a locking pawl 26' at one end which is retractably inserted through the locking-pawl-insertion hole, an engaging leg 22' at the other end which is inserted in the engaging recess, the pair of horizontal pivot pins 23' disposed on its opposite side surfaces toward the front cover-attachment projection 12', and a resilient tongue 24' obliquely projecting from its upper surface. On the other hand, a cover 4' has in front and rear end walls a pair of engaging through-holes in which the front and rear cover-attachment projections 12' are engaged. In assembling, an axle 20' of a pull tab 2' is placed on the upper wing 7' of the slider body 1' between the locking-pawl-insertion hole 16' and the pivot supporting portions 15', and then the locking member 3' is mounted astride of the axle 20' of the pull tab 2', with the locking pawl 26' inserted in the locking-pawl-insertion hole 16' and with the engaging leg 22' received in the recess 14', whereupon the cover 4' is attached to the upper wing 7' by engaging the hooks 13' with the engaging through-holes so as to conceal the locking member 3'. This conventional slide fastener slider is disclosed in Republic of China Patent Publication No. 248646.
In the first-named slider in which the cover is attached to the slider body 1' by clenching or welding, since the clenching step or the welding step must be added to the automatic assembling process, it is impossible to realize a high-speed automatic assembling process and hence production rate can not be improve particularly in the case of thermoplastic resin slider.
In the case of the slider shown in FIG. 20, since the front and rear cover-attachment projections 12' on the upper wing 7' of the slider body 1' engage in the engaging through-holes of the cover 4', the projections can be seen to make the appearance of the slider unsightly, deteriorating the commercial value of the product. Further, since the slider body 1' has on the upper wing 7' no guide for the axle 20' of the pull tab 2', it is impossible to guide the axle 20' of the pull tab 2' reliably and smoothly, thus causing non-stable operation of the pull tab 2'.